Weed Wacker Revisited.

Great running dialogue with lots of good information, Deacon. tnx!
I'll drill out the mounting holes now, and get that over with.

CB2... Tnx I shall fab an air scoop for cooling. No plans for idling in traffic, but as they say, plans rarely survive implementation ! LoL
I had made plans for a scissor lift to raise the engine roller up off the tire when stopped. I suppose I can shut down and re-start if stopped for more than a common traffic light. There ain't many in my two-horse two, anyway.


....More pics, Deacon!
I like pics ! :-)


Best
rc
 
I was going to say you can always shut it down then drag it off again when you need to go. I love that about these little engines. They are probably the safest ones around. Put on all your brakes and the engine will die harmlessly. Then a couple of pedals and drop it then hold on cause it is going to start with a jolt. It's a fun ride. I have a rattling sound I can't fine when the engine is on the tire. I am expecting it to explode any minute lol.

Tomorrow morning first thing, I am going to pull my motor off the frame and tap those holes. I want to make this as sturdy as I can. Lowes here has 3/4" long 1/4 bolts they should work well with a lock washer and some super glue gell on the threads

Now that I know the power band, it is worth spending some more time on it.
 
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Yes it looks like carp but it is the prototype. Next one will be from new material (I'm thinking aluminum channel) and it will be square and level. Right now this one works so for now I'm going to just ride it, but I will be making a new mount soon.

Now I have one more thing (there is always one more thing) to find out. Can I take the cold motor, primer the carb set the choke on half choke and drag start the engine. Then lift it and set it on no choke just like you do the kit bikes. I would rather eliminate the rope start if possible.
 
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Cool Deek! Is that a wheel hub it pivots on? You should have no problem starting like you mention. However you will have little to no cooling with out the fan shroud. Gut the recoil and see if you can fit the shroud, will have to open the hole size where the recoil was to accomadate the roller. Need to get some air through the cylinder
 
Deacon,

Wow! Ur welding s***s !

...Sry, the devil made me say it! LoL

Great test bed. That's what counts.
I am learning and considering more options just from viewing your pics!

I have kinda planned for some sort of abbreviated shroud, hammered from lite sheet stock, to direct some air from the central crank area through the centrifugal fan, OR, a scoop as CB2 suggested if I'm NOT going to idle the engine. I did mill down the fan blades on my flywheel, so the roller was not hanging out so far from the sole bearing support in the engine. My machined roller also has an outboard bearing which I'll need to support on the opposite side of the fork supporting the engine.

On a thread elsewhere, a member has requested engineering support regarding a bicycle frame... I think some could be used here, in relation to the swing angle of the mount in relation to the contact point of the roller upon the tire.
Where you employ a spring to force the drive assembly, it should be possible, with the correct geometry, for the roller to 'dig' into the tire when power is applied, and the function of lift on the assembly should actually limit the amount of friction applied to the drive mechanism. A certain amount of spring tension will always be required, to mediate irregularities, but that, and the weight of the power unit should not be the controlling factor for the drive.
IMO LoL! Just some thoughts that have come to mind, viewing your pics...
FWIW

Good work Deacon! I enjoy your thread a lot.
Best
rc
 
I actually use the clutch cable to set the drive tension, I tension it until I get slip under heavy throttle then start backing off until it gets just to the point where it doesnt slip. I actually do this while riding. Of course it only works like this with a lift clutch.
 
I usually lay mine on the wheel then turn the turnbuckle a few times to tighten it. I can increase or back off. If you have to have a spring to hold the roller from bouncing up and down, might as well use it for the tension as well.

My welding skills are garbage. Some times they hold sometimes they don't. It is a pure carp shoot. lol...
One day I will rebuild that frame. I might duct tape the shroud back on. I am using the holes screw holes for the mount.

One of the many things I like about this engine is the gas tank being where it is makes it possible to use it instead of adding a new one. I can just use one of the many I have to carry extra gas to get me home if I run out.

I did try the starting and it works pretty well so far. Since it is hard to get a rope start into the frame, it makes the bike a lot more user friendly.

One last thing IMHO the lift clutch is the way to go with the WW. The engine is lightweight and if you run our of gas you can lift it lock it up and go home with it.

you know the more I think about duct taping the housing the more I like it. It would have just the right feel for the rest of the build.
 
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I rode the bike after four hours, I figured that was cold enough to check the start. I also wanted to see if I could make it to the lake and back on one tank of gas, and it looks like I can.

The bike started just fine, so I think I will be starting it that way routinely from now on. I just need to remember to drop the engine gently onto the tire. The engine continues to do well even though the case will not go back on it. The mount is in the way of it. With the mount the drive spindle would be way too long. I think I will trade the heat for the extra stain on the drive shaft for now. Even though it isn't directed the fan is still creating air movement as is the engine moving through the air. Will it be enough, we will soon see.
 
The almost one inch roller I had on the WW bike flew apart today. I'm not a bit surprised. I had used a pipe nipple with a washer that was spot welded on for a different purpose entirely. I should have done a real welding job on ti as bad as my welding is.

Anyway when I got the WW home I found it to be a no harm no foul situation. I had a BMX axle peg I had planned to use on another build and didn't, so I put that onto the flywheel and tightened it down a bunch. It is about two inches in diameter outside. It is totally smooth so I didn't expect much difference. It is a lot different. The bike goes faster climbs most hill okay at higher speed, but it does poop out on some of the really long steep ones. I don't mind the extra pedaling though, so it is fine.
 
Thanks for the reports on the experiments, Deacon.
I read every single one!
Your results have led me to reconsider a lot of things I might have done that would not have worked out quite so well.

Ha! I was just joshing you over the welding... if it works for the prototypes, run it! I still tack mild steel using coat hanger wire and weld copper with stripped electrical wire scraps. I've got fancy store-bought rod, but save it for projects that are critical to me. I'm a cheapskate!

100mph tape is a good product because the adhesive is flexible and will not randomly give out due to vibration. But it will give up! OK for experimenting, but if left on for too long, however long that is, watch out for things sailing through the spokes!
IMO Nashua brand duct tape is the best, and the 'lathers' use a red colored duct tape in construction for putting up their plastic that will handle wet surfaces better, which could be something you might run into when on a bicycle...

Best
rc
 
Most of the ugly welding is steel that has been welded ground off and then reused without proper cleaning. Some hold some doesn't but my welds look like i did them. This afternoon I built a new frame for the motor. It is the same as the last one only everything is level and square. I did it because the other one just looked like it was going to come apart any minute. Kind of like that spindle I did nothing about until it left me on the road.

The big roller is much different than the smaller one. I think I might start looking for a smaller one again. Drag starting is the way to go with these things. I hate that pull rope so it seems to work pretty well no matter how cold the engine is.
 
Hey Deacon,

I agree that a bump start is probably best for these little rack mount friction drives. A recoil starter is a handy convenience for a homeowner with a less mobile application.

Since we're dealing with a machine that requires a pedal start even when running, might as well leash some of that momentum to start the motor assist !

You'll probably find the engine starts better with the larger roller because the friction is superior because of the larger bearing surface, and the ratio will spin it faster at start. Of course the smaller pinion will perform better all around because it is more suited to the torque and rpm range of the engine, suffering only because of friction bearing surface at the tire.

When I looked at your pics the other day I thought you might benefit well from an $8 wallyworld chengshin cruiser tire instead of your MTB tire which is nearly gone, anyway. A thorn guard might be a good idea, too, to help with dealing with the additional heat generated by the friction drive. Perhaps others could present some input on that effect.

...a number of years back, a kid on a mini-bike pulled up to where I was working, to talk with a friend of his that was part of my work crew. It was stripped down to the basics... I expect a lot of parts had fallen off or gotten lost. Lol

After his short conversation, he put his foot on the flywheel and spun it forward with his tennis shoe, the briggs started, and he took off.
It's all good !

I didn't mean to throw you under the bus over the welding, Deacon. If it gets the job done, that counts. ...Recently I've been participating over at the Longevity welding forum and the fellows are showing off their fabulous welds on any number of projects... my own aren't near up to their standards. Some do textbook quality welding in their posts. They are beautiful. One small variation in a bead may generate a dozen responses, in great detail, on techniques to resolve the situation. It's educational, and fun.
My own tig welds would never meet their standards! LoL

Best
rc
 
Oh i didnt mind at all. My wife and I joke about my welding all the time. The worst was when I left right after welding out my shop door in the fall. I should have looked more closely the leaves near where I was welding was on fire. My neighbor saw it and stamped out the leaves. I found a smoldering mess inside the wall when I got home. No real damage but embarrassing.

Now when she jokes with me, I say let me set fire to the house one time with my welder and I never hear the end of it. The way I build is to put in a bolt, the weld it to keep it from moving, when the bolt gets loose. I have a neighbor who is a good welder. If I have something important I take it to him.

His advice to me was, but a grinder and a can of black paint. I have both lol.
 
...know what you mean, Deacon... years back I wanted to teach our boys to gas weld, mentioned it to a friend, and he pointed out the fire potential in our area... summer, this place is a tinderbox... so I thought it wise to pass until the boys were older and more responsible.

..the biggest fires around here were all started by the forestry department when a controlled burn got away from them... 2nd in line has been someone doing weed abatement makes a spark and sets something off. 3rd is lightning strikes.

When I get my MABs going, I'll need to install a .022 ss arrestor screen just to make sure the are no problems on my account. That would be a bad thing.

Best
rc
 
I live in the city so we don't have those kinds of fires.

The pretty welding thing reminds me of my dad. My dad was a hunter and a fisherman. A real outdoors type. He drove trucks that were real trucks, not these cars with a pickup bed on them. So one day some asked him "Fred why don't you buy a family car. It would be a much better ride for your family."

My dad says, "A car or truck is to get you from here to there. Fifteen minutes after you get there, you won't really remember how you got there." I add if the place was worth going to in the first place..cs.
 
I guess now I'm just looking for things to do to the bike. I removed the cable from the lift and ran solid links instead. I had a bunch of stretcher bars for use in chain link fences so I cut one of them down to make a link to replace the cable. The link might lose a nut but a broken cable is harder to deal with on the road. I build with all the same size nuts and bolts so I could carry and extra one or two. I need to do that anyway.

I rode the bike to the home depot this morning and it was fun. Get lots of interest in the bike. This kind of bike would make a nice kit project. Since I am doing drag start it would be okay for a kit now. No I have no interst in making once but it would be a good one. next project is to make a better throttle cable for it. Now I am using the cable that was on the week wacker joined to a cable from the bike. That works fine except that when you lift the engine it gos back to idle because the two cable piecs are attached at different points. I have to fix that.
 
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cable repaired and the black basket attached. Not much left I can do to this one. Now I just need to learn to get it going without so much drama. Im not letting it warm up enough before I take off on it. So from now on I have to be cognizant of that.
 
I have been thinking I want to build the absolute fantasy bike. Since I can build a very simple bolt on thing now. What I build now requires very little modification to the bike. The bike can have no rear fender and I have to have or add a front brake for safety but otherwise any bike will do. The frame I use now is just big and clunky which I like but I think something outrageous is next. If I ever do another.

I'm thinking the most girlie 2o" bike possible from the thrift shop. You know the kind one with purple wheels and a princess decal somewhere. I would love to strap a WW Engine on the back of that lol.

Oh yeah, I rode the bike today keeping starting simple. So here is how the drag start works best for me. Primer it... set the choke on half choke. pedal a few time when it first starts lift the engine and stop. let the bike warm up slowly for a couple of minutes minimum. then I set the throttle at about 1/4 and ease the motor down. seems to work the best.
 
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I finally pulled the fly wheel on the motor that I destroyed and yes I broke the key. I also don't seem to have much compression on the engine. I probably did some damage I can't see. But at least now I know what parts are salvageable. Not too many actually.
 
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